U.S. patent number 8,315,193 [Application Number 11/855,082] was granted by the patent office on 2012-11-20 for ad-hoc network power save system and method.
This patent grant is currently assigned to Marvell World Trade Ltd.. Invention is credited to Kapil Chhabra.
United States Patent |
8,315,193 |
Chhabra |
November 20, 2012 |
AD-HOC network power save system and method
Abstract
Symmetrical and asymmetrical ad-hoc, wireless networks and a
method for saving power in the same may include causing a first
station to determine whether a second station has a master
capability to buffer data traffic for the first station. A first
station requests the second station to buffer the data traffic
intended for the first station for a first predetermined period.
The first station enters a first power save mode, and the second
station buffers the data traffic for the first station for the
first predetermined period. The first station exits the first power
save mode after the first predetermined period and the second
station sends the buffered data traffic to the first station. Both
the first and second stations may have master capabilities, or only
one of the first and second stations may have a master
capability.
Inventors: |
Chhabra; Kapil (Sunnyvale,
CA) |
Assignee: |
Marvell World Trade Ltd. (St.
Michael, BB)
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Family
ID: |
39184339 |
Appl.
No.: |
11/855,082 |
Filed: |
September 13, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080069021 A1 |
Mar 20, 2008 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60825611 |
Sep 14, 2006 |
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Current U.S.
Class: |
370/311 |
Current CPC
Class: |
H04M
1/72412 (20210101); H04W 84/18 (20130101); H04W
52/0219 (20130101); H04M 2250/06 (20130101); H04W
52/0274 (20130101); Y02D 30/70 (20200801); H04W
28/14 (20130101); H04M 1/6066 (20130101); H04M
1/2535 (20130101) |
Current International
Class: |
G08C
17/00 (20060101); H04M 1/00 (20060101) |
Field of
Search: |
;370/310,311
;455/73,343.2,426.2,572,574 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2004-336401 |
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Nov 2004 |
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JP |
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2004-363702 |
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Dec 2004 |
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JP |
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2005-130436 |
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May 2005 |
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JP |
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2007-528641 |
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Oct 2007 |
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JP |
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WO-2005/064952 |
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Jul 2005 |
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WO |
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Other References
International Search Report in corresponding PCT/US07/19885 mailed
Apr. 18, 2008. cited by other .
Written Opinion in corresponding PCT/US07/19885 mailed Apr. 18,
2008. cited by other .
Office Action in corresponding Chinese Application No.
2011052600602350 mailed May 31, 2011. cited by other .
Specification of the Bluetooth System, Version 2.0: vol. 0, "Master
Table of Contents & Compliance Requirements," pp. 1-74; vol. 1,
"Architecture & Terminology Overview," pp. 1-92; vol. 2, "Core
System Package [Controller Volume]", pp. 1-814; vol. 4, "Core
System Package [Host Volume]," pp. 1-250, Nov. 4, 2004. cited by
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International Preliminary Report on Patentability in corresponding
PCT/US07/19885 mailed Mar. 17, 2009. cited by other .
International Standard, ISO/IEC 8802-11, ANSI/IEEE Std 802.11,
"Information technology--Telecommunications and information
exchange between systems--local and metropolitan area
networks--specific requirements" Part 11: Wireless LAN Medium
Access Control (MAC) and Physical Layer (PHY) specifications, The
Institute of Electrical and Electronics Engineers, Inc., (1999).
cited by other .
Pering, et al., "CoolSpots: Reducing the Power Consumption of
Wireless Mobile Devices with Multiple Radio Interfaces," Fourth
Int'l Conf. on Mobile Systems, Applications, and Services, Uppsala,
Sweden (MobiSys 2006) pp. 220-232 (2006). cited by other .
Office Action in corresponding Japanese Application No. 2009-528282
mailed Apr. 24, 2012. cited by other .
"Unapproved Draft Standard for Information
Technology-Telecommunications and information exchange between
systems--Local and metropolitan area network--Specific requirements
Part 11: Wireless LAN Medium Access Control (MAC) and Physical
Layer (PHY) specifications. (This document reflects the combining
of the 2003 Edition of 802.11 plus the 802.11 g, 802.11 h, 802.11 i
and 802.11j Amendments) (Revision of IEEE Std 802.Nov. 1999)," IEEE
Std P802.11-REVma/06.0, vol., No., 2006. cited by other .
IEEE Std 802.Nov. 2007 (revision of IEEE Std. 802.Nov. 1999)
"Information Standard for Information
technology--Telecommunications and information exchange between
systems--Local and metropolitan area networks--Specific
requirements" Part 11: Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) Specifications, The Institute of Electrical
and Electronics Engineers, Inc., (Jun. 12, 2007). cited by
other.
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Primary Examiner: Pham; Chi
Assistant Examiner: Lopata; Robert
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application
No. 60/825,611, filed on Sep. 14, 2006. The disclosure of the above
application is incorporated herein by reference in its entirety.
Claims
What is claimed is:
1. A method for saving power in an ad-hoc network including a first
station and a second station, wherein each of the first station and
the second station has a corresponding network interface configured
to wirelessly communicate with other stations in the ad-hoc
network, the method comprising: transmitting, from the first
station, a first advertisement of a capability of the first station
to buffer data traffic intended for other stations; receiving, at
the first station, a second advertisement of a capability of the
second station to buffer data traffic intended for other stations;
after transmitting the first advertisement and in response to
receiving, from the second station, a first request to buffer data
traffic intended for the second station for a first predetermined
period, wherein the first request is in response to the first
advertisement, i) transmitting, from the first station, a response
to the first request, ii) buffering, at the first station, data
traffic intended for the second station during the first
predetermined period, and iii) transmitting, from the first station
to the second station, the buffered data traffic intended for the
second station after the first predetermined period elapses; and
after transmitting the first advertisement, after receiving the
second advertisement, and in response to transmitting, from the
first station, a second request to the second station to buffer
data traffic intended for the first station for a second
predetermined period, i) receiving, from the second station, a
response to the second request, ii) causing the first station to
enter a first power save mode for the second predetermined period,
and iii) receiving, at the first station, the buffered data traffic
intended for the first station after the second predetermined
period elapses.
2. The method of claim 1, further comprising in response to
receiving, at the first station, the first request to buffer data
traffic intended for the second station, iv) preventing the first
station from entering the first power save mode.
3. The method of claim 2, wherein preventing the first station from
entering the first power save mode occurs when the first request
from the second station is received within a third predetermined
period from when the first station transmits the second request to
the second station.
4. The method of claim 2, further comprising, in response to
receiving, at the first station, the first request to buffer data
traffic intended for the second station: computing, at the first
station, a random back-off period; and in response to the back-off
period elapsing, transmitting, from the first station, a third
request to buffer data traffic intended for the first station for
the second predetermined period.
5. The method of claim 1, further comprising causing the first
station to enter the first power save mode when the second station
enters a second power save mode.
6. The method of claim 5, further comprising causing the first
station to exit the first power save mode before the second station
exits the second power save mode.
7. The method of claim 1, wherein the ad-hoc network is a wireless
network using a protocol selected from the group consisting of IEEE
802.11 standards and Bluetooth standards.
8. A method for saving power in an ad-hoc network including a first
station and a second station, wherein each of the first station and
the second station has a corresponding network interface configured
to communicate with other stations in the ad-hoc network, the
method comprising: transmitting, from the first station, an
advertisement of a capability to buffer data traffic intended for
other stations; after transmitting the advertisement, receiving, at
the first station, a request to buffer data traffic intended for
the second station for a predetermined period, wherein the request
is in response to the advertisement; and in response to receiving
the request to buffer data traffic intended for the second station,
i) transmitting, from the first station, a response to the request
to buffer data traffic intended for the second station, ii)
buffering, at the first station, data traffic intended for the
second station during the predetermined period, and iii)
transmitting, from the first station, the buffered data traffic
intended for the second station to the second station after the
predetermined period elapses.
9. The method of claim 8, further comprising causing the first
station to enter a power save mode during a portion of the
predetermined period.
10. The method of claim 9, further comprising causing the first
station to exit the power save mode before an end of the
predetermined period.
11. The method of claim 8, wherein the ad-hoc network is a wireless
network using a protocol selected from the group consisting of IEEE
802.11 standards and Bluetooth standards.
12. The method of claim 8, wherein the first station is a master
station and the second station is a slave station.
13. A first station for use in an ad-hoc network, the first station
comprising: a network interface, wherein the network interface is
configured to: transmit a first advertisement of a capability of
the first station to buffer data traffic intended for other
stations; receive, from a second station, a second advertisement of
a capability of the second station to buffer data traffic intended
for other stations; after transmitting the first advertisement and
in response to receiving, from the second station, a first request
to buffer data traffic intended for the second station for a first
predetermined period, wherein the first request is in response to
the first advertisement, i) transmit a response to the first
request, ii) buffer data traffic intended for the second station
during the first predetermined period, and iii) transmit the
buffered data traffic intended for the second station to the second
station after the first predetermined period elapses; and after
transmitting the first advertisement, after receiving the second
advertisement, and in response to transmitting a second request to
the second station to buffer data traffic intended for the first
station for a second predetermined period , i) receive, from the
second station, a response to the second request, ii) cause the
first station to enter a first power save mode for the second
predetermined period, and iii) receive, from the second station,
the buffered data traffic intended for the first station after the
second predetermined period elapses.
14. The first station of claim 13, wherein the network interface is
further configured to, in response to receiving, from the second
station, the first request to buffer data traffic intended for the
second station, iv) prevent the first station from entering the
first power save mode.
15. The first station of claim 14, wherein the network interface is
further configured to prevent the first station from entering the
first power save mode when the first request from the second
station is received within a third predetermined period from when
the first station transmits the second request to the second
station.
16. The first station of claim 13, wherein the network interface is
further configured to, in response to receiving, from the second
station, the first request to buffer data traffic intended for the
second station: compute a random back-off period; and in response
to the back-off period elapsing, transmit a third request to buffer
data traffic intended for the first station for the second
predetermined period.
17. The first station of claim 13, wherein the network interface is
further configured to cause the first station to enter the first
power save mode when the second station enters a second power save
mode.
18. The first station of claim 17, wherein the network interface is
further configured to cause the first station to exit the first
power save mode before the second station exits the second power
save mode.
19. The first station of claim 13, wherein the ad-hoc network is a
wireless network using protocol selected from the group consisting
of IEEE 802.11 standards and Bluetooth standards.
20. A first station for use in an ad-hoc network, the first station
comprising: a network interface, wherein the network interface is
configured to: transmit an advertisement of a capability to buffer
data traffic intended for other stations; after transmitting the
advertisement, receive, from a second station, a request to buffer
data traffic intended for the second station for a predetermined
period, wherein the request is in response to the advertisement;
and in response to receiving the request to buffer data traffic
intended for the second station, i) transmit, to the second
station, a response to the request, ii) buffer data traffic
intended for the second station during the predetermined period,
and iii) transmit the buffered data traffic intended for the second
station to the second station after the predetermined period
elapses.
21. The first station of claim 20, wherein the network interface is
further configured to cause the first station to enter a power save
mode for a portion of the predetermined period.
22. The first station of claim 21, wherein the network interface is
further configured to cause the first station to exit the power
save mode before an end of the predetermined period.
23. The first station of claim 20, wherein the ad-hoc network is a
wireless network using protocol selected from the group consisting
of IEEE 802.11 standards and Bluetooth standards.
24. The first station of claim 20, wherein the first station is a
master station and the second station is a slave station.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to a power save system in a network
and, more particularly to a periodic power save system in an ad-hoc
wireless network.
2. Related Art
A wireless network (e.g., Wi-Fi based on IEEE 802.11 standards) may
be characterized as an infrastructure mode network or an ad-hoc
mode network depending on whether the stations within the wireless
network can directly communicate with other stations in the
network. FIG. 1(A) illustrates an example of an infrastructure mode
wireless network, which may typically comprise an access point 2
and stations 4, 6 and 8. In the infrastructure mode network, the
stations 4, 6 and 8 are not configured to directly communicate with
each other, and any communication between the stations 4, 6 and 8
must be channeled through the access point 2.
In contrast, an ad-hoc mode network allows each station to
communicate directly with each other, as illustrated in FIG. 1(B).
Thus, in the ad-hoc mode wireless network, there is no central
access point controlling communication among the stations 4, 6 and
8. Ad-hoc devices are configured to communicate only with other
ad-hoc devices, and they are not able to communicate with any
infrastructure devices or any other devices connected to a wired
network.
Considering that a significant portion of the Wi-Fi devices are
portable devices (e.g., cellular phones, portable gaming devices,
wireless headsets, wireless headphones, wireless speakers and the
like), power consumption has become an important issue for the
Wi-Fi devices. This has led the IEEE to standardize the
infrastructure mode network power save protocol. However, due to
the decentralized nature of ad-hoc mode networks, it is much more
difficult and complicated to implement power save algorithms when
there is no central access point that dictates all the decisions
related to power consumption in the network.
SUMMARY OF THE INVENTION
The invention allows ad-hoc network devices to enter a power save
mode. The invention also provides for power consumption decisions
to be made in an ad-hoc network to improve implementation of power
save algorithms. Other advantages and benefits of the invention are
apparent from the discussion herein.
Accordingly, in one aspect of the invention, a method for saving
power in an ad-hoc network including first and second stations each
having a wireless capability to directly communicate with each
other includes issuing a request to the second station to buffer
data traffic intended for the first station for a first
predetermined period, granting the request to buffer data traffic,
causing the first station to enter a first power save mode for the
first predetermined period, and enabling the second station to
buffer data traffic intended for the first station for the first
predetermined period.
The method may further include causing the first station to exit
the first power save mode after the first predetermined period
elapses, and sending the buffered data traffic to the first
station. Sending the buffered data traffic may include sending the
buffered data traffic from the second station to the first station.
The method may further include causing the first and second
stations to simultaneously enter a second power save mode for a
second period time. The method may further include advertising a
master capability of the second station to buffer data traffic
intended for the first station. The method may further include
causing the second station to exit the second power save mode
before the first station exits the second power save mode. The
ad-hoc network may be a wireless network using protocol selected
from the group consisting of IEEE 802.11 standards and Bluetooth
standards. The method may further include determining whether the
second station has a capability to buffer data traffic intended for
the first station. The method may further include issuing a request
to the first station to buffer data traffic intended for the second
station for a second predetermined period, granting the request to
buffer data traffic intended for the second station, causing the
second station to enter a second power save mode for the second
predetermined period, and enabling the first station to buffer the
data traffic intended for the second station for the second
predetermined period. The method may further include causing the
second station to exit the second power save mode after the second
predetermined period elapses, and sending the buffered data traffic
to the second station. Sending the buffered data traffic to the
second station may include sending the buffered data traffic from
the first station to the second station. The method may further
include determining whether the first station has a capability to
buffer data traffic intended for the second station. The method may
further include preventing the first station from entering the
first power save mode if the second station requests the first
station to buffer the data traffic intended for the second station,
and preventing the second station from entering the second power
save mode if the first station requests the second station to
buffer the data traffic intended for the first station. The method
may further include preventing the first station from entering the
first power save mode occurs if the request is received within a
predetermined period of time from when the first station sends such
a request, and preventing the second station from entering the
second power save mode occurs if the request is received within a
predetermined period of time from when the second station sends
such a request. The method may further include causing the slave
station to exit the power save mode after the predetermined period
elapses, and causing the master station to send the buffered data
traffic to the slave station. The method may further include
advertising a master capability of the master station to buffer
data traffic intended for any of the plurality of stations in the
ad-hoc network, and determining if the master station has the
master capability to buffer data traffic intended for one of the
plurality of stations. The ad-hoc network may be a wireless network
using a protocol selected from the group consisting of IEEE 802.11
standards and Bluetooth standards.
According to another aspect of the invention, a method for saving
power in an ad-hoc network including a plurality of stations, the
plurality of stations including a master station and at least one
slave station incapable of buffering traffic for other stations,
each station having a wireless capability to directly communicate
with other stations, includes issuing a request to the master
station to buffer data traffic intended for the slave station for a
predetermined period, granting the request to buffer data traffic,
causing the slave station to enter a power save mode for the
predetermined period, and enabling the master station to buffer
data traffic intended for the slave station for the predetermined
period.
The first station has a master capability to buffer data traffic
intended for other stations in the ad-hoc network for a second
predetermined period and may be configured to grant a request from
the second station to allow the second station to enter a second
power save mode, and wherein the second station may be configured
to determine if there may be any station having the master
capability in the ad-hoc network. The second station may enter the
second power save mode for the second predetermined period when the
first station grants the request from the second station, and the
first station sends the buffered data traffic to the second station
after the second predetermined period elapses. The first station
may be configured not to enter the first power save mode if the
second station requests the first station to buffer the data
traffic intended for the second station, and the second station may
be configured not to enter the second power save mode if the first
station requests the second station to buffer the data traffic
intended for the first station. The first station may not enter the
first power save mode if the request is received within a
predetermined period of time from when the first station sends such
a request, and wherein the second station may not enter the first
power save mode if the request is received within a predetermined
period of time from when the second station sends such a request.
The master and slave stations may be configured to simultaneously
enter a second power save mode for a second period time. The master
station may be configured to exit the second power save mode before
the slave station exits the second power save mode. The ad-hoc
network may be a wireless network using a protocol selected from
the group consisting of IEEE 802.11 standards and Bluetooth
standards.
In yet another aspect of the invention, an ad-hoc network includes
a first station having wireless communication capabilities and
configured to determine if there is any station in the ad-hoc
network having a master capability to buffer data traffic intended
for other stations in the ad-hoc network for a first predetermined
period, the second station having wireless communication
capabilities and the master capability and configured to grant a
request from said first station to allow said first station to
enter a first power save mode, and wherein the first station enters
the first power save mode for the first predetermined period when
the second station grants the request and the second station sends
the buffered data traffic to the first station after the first
predetermined period elapses A system for saving power in an ad-hoc
network including first and second stations each having a wireless
capability to directly communicate with each other, the system
further includes means for issuing a request to the second station
to buffer data traffic intended for the first station for a first
predetermined period, means for granting the request to buffer data
traffic, means for causing the first station to enter a first power
save mode for the first predetermined period, and means for
enabling the second station to buffer data traffic intended for the
first station for the first predetermined period.
A machine-readable medium including stored instructions, which,
when executed by a processor cause the processor to implement power
saving in an ad-hoc network having a plurality of stations, the
instructions including instructions for determining whether a first
one of the stations has a capability to buffer data traffic
intended for a second station, instructions for requesting the at
least one station to buffer data traffic intended for the second
station for a first predetermined period, instructions for granting
a request to buffer data traffic intended for the second station,
instructions for causing the second station to enter a first power
save mode for the first predetermined period, and instructions for
enabling the first one station to buffer data traffic intended for
the second station for a second predetermined period, instructions
for causing the second station to exit the first power save mode
after the first predetermined period elapses, and instructions for
sending the buffered data traffic to the second station.
Additional features, advantages, and embodiments of the invention
may be set forth or apparent from consideration of the following
detailed description, drawings, and claims. Moreover, it is to be
understood that both the foregoing summary of the invention and the
following detailed description are exemplary and intended to
provide further explanation without limiting the scope of the
invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to provide a further
understanding of the invention, are incorporated in and constitute
a part of this specification, illustrate embodiments of the
invention and together with the detailed description serve to
explain the principles of the invention. No attempt is made to show
structural details of the invention in more detail than may be
necessary for a fundamental understanding of the invention and the
various ways in which it may be practiced. In the drawings:
FIGS. 1(A) and 1(B) illustrate an example of an infrastructure mode
network and ad-hoc mode network, respectively;
FIG. 2(A) and 2(B) illustrate examples of a symmetrical ad-hoc
network;
FIG. 3(A), 3(B) and 3(C) illustrate examples of a asymmetrical
ad-hoc network;
FIG. 4(A) is a flow chart for a power save scheme in a symmetrical
ad-hoc network constructed according to the principles of the
invention; and
FIG. 4(B) is a flow chart for a power save scheme in an
asymmetrical ad-hoc network constructed according to the principles
of the invention.
FIGS. 5-12 show various exemplary implementations of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
The embodiments of the invention and the various features and
advantageous details thereof are explained more fully with
reference to the non-limiting embodiments and examples that are
described and/or illustrated in the accompanying drawings and
detailed in the following description. It should be noted that the
features illustrated in the drawings are not necessarily drawn to
scale, and features of one embodiment may be employed with other
embodiments as the skilled artisan would recognize, even if not
explicitly stated herein. Descriptions of well-known components and
processing techniques may be omitted so as to not unnecessarily
obscure the embodiments of the invention. The examples used herein
are intended merely to facilitate an understanding of ways in which
the invention may be practiced and to further enable those of skill
in the art to practice the embodiments of the invention. For
example, the invention is described in terms of Wi-Fi network based
on IEEE 802.11 standard, but it will be understood that the
invention is not so limited. The invention may be broadly
applicable to any ad-hoc mode wireless network and other types of
wireless networks that have appropriate features and
characteristics. Accordingly, the examples and embodiments herein
should not be construed as limiting the scope of the invention,
which is defined solely by the appended claims and applicable law.
Moreover, it is noted that like reference numerals represent
similar parts throughout the several views of the drawings.
The invention relates to periodic power save protocols for ad-hoc
networks. Different devices within the ad-hoc network can take on
the role of a master while the other slave devices enter a power
save mode. The master device receives data for the other devices
and sends the buffered data when those slave devices wake up. This
protocol allows for power savings among the devices. Various
aspects of the invention will now be described in greater detail
below.
FIGS. 2(A), 2(B), 3(A), 3(B) and 3(C) illustrate examples of an
ad-hoc mode network configuration. Depending on similarity of
capabilities among the devices (i.e., stations, nodes or the like)
in the network, the ad-hoc mode network may be characterized as a
symmetrical ad-hoc mode network or an asymmetrical ad-hoc mode
network. FIGS. 2(A) and 2(B) illustrate examples of the symmetrical
ad-hoc mode network, in which the devices may have similar
capabilities, such as, for example, processing power, memory,
battery life or the like. In particular, FIG. 2(A) illustrates two
walkie-talkies or cellular phones 12 and 14 with identical or
substantially the same capabilities connected via an ad-hoc mode
network. This connection allows real-time multi-user voice
communication via the ad-hoc mode network. When the devices 12 and
14 are not in use, it may be necessary to turn off one or both
devices to save power. Since there is no central access point to
carry out a power save mode, a power save protocol may be carried
out on all devices in the network without overburdening any
particular device. For example, each of the devices 12 and 14 may
alternatively take charge by acting as a master device that carries
out power save algorithms in the network.
Similarly, FIG. 2(B) illustrates two identical portable gaming
devices 16 and 18 (e.g., Sony.TM. PSP.TM. or the like) connected to
each other via an ad-hoc mode network. This connection may provide
real-time multi-player gaming experiences for those using the
portable gaming devices 16 and 18. When the devices 16 and 18 are
not being used, the devices 16 and 18 may communicate with each
other to decide which device will take charge as a "master" to
carry out a power save protocol for the network. The "master"
device may allow other devices (i.e., slaves) in the network to
enter a power save mode and buffer data traffic for the slave
devices, which will be also described below in detail. It should be
understood that walkie-talkies, cell phones and gaming devices are
merely illustrative of the type of devices that may be connected in
a symmetrical, ad-hoc network.
FIGS. 3(A), 3(B) and 3(B) illustrate examples of the asymmetrical
ad-hoc mode network configuration, in which the ad-hoc devices have
different capabilities. For example, FIG. 3(A) illustrates an
asymmetrical ad-hoc mode network including a cellular phone 20 and
a wireless headset 22. Typically, the wireless headset 22 is
provided with significantly less capabilities than the cellular
phone 20 and may not be able to carry out the power save algorithms
for the ad-hoc network. In this case, the power save protocol may
exploit the capabilities of the cellular phone 20, which may
permanently take charge as a master while the headset 22
permanently operates as a slave in this situation. Similarly, FIG.
3(B) illustrates a PC 24 and a wireless headphone 26 connected to
each other via an ad-hoc mod network, wherein the PC 24 operates as
the master while the wireless headphone 26 operates as the slave in
carrying out the power save mode. In FIG. 3(C), an audio device 30
with more capabilities may carry out the power save mode as a
permanent master to wireless speakers 32. Again, these examples are
merely illustrative of the type of devices that may be connected in
an asymmetrical, ad-hoc network.
FIG. 4(A) illustrates a flow chart for a power save scheme in a
symmetrical ad-hoc network constructed according to the principles
of the invention. As mentioned above, in a symmetrical ad-hoc mode
network, each device may have capabilities to carry out power save
algorithms in the network as a master. Thus, it is assumed that
stations A and B (e.g., walkie-talkies 12 and 14 in FIG. 2(A),
respectively) are both equally capable of carrying out the power
save algorithms without overburdening the other one. As shown in
steps 40 and 42, stations 12 and 14 both advertise their master
capabilities to other stations in the network. The master
capabilities may include an ability to buffer data designated for
other stations in the network that are in a sleep (power save)
mode. After confirming that station B has master capabilities,
station A may send a power save enter request to station B, as
shown in step 44. The power save enter request may be included in
an uplink IEEE action management frame of station A's beacon that
is sent to station B. The frame may include information about the
sleep period of station A. The power save enter request may be
included in an uplink IEEE action management frame sent from slave
to master. The capability to implement this protocol may be
advertised in the station beacons and probe responses. The power
save enter request/response may be sent using IEEE Action
Management frames. Further, the power save enter request may
include information about the slave station's frequency of wake-ups
(referred to as sleep period), while the power save enter response
may include information about a number of service periods the
master may buffer traffic for slave.
It is possible that both stations A and B send their respective
power save enter requests to each other. To avoid the conflict,
each station may be configured to stay in a full power mode when
the request is received from other stations. Each station may then
compute a random back-off and re-attempt to enter the power save
mode when the back-off expires or stay in full power mode as the
master if other station's back-off expires earlier.
Upon accepting the request from station A, station B becomes the
master and station A becomes the slave. As shown in step 46,
station B may send a power save enter response to station A. The
power save enter response may be included in an IEEE action
management frame. The power save enter response may contain the
maximum number of service periods during which the master station B
will buffer data traffic for slave station A. According to an
embodiment of the invention, a service period may be defined as the
period between receiving an uplink trigger from slave station A to
the point where master station B sends an end of service period
(EOSP) indication. Each uplink frame with a trigger bit set from
slave station A may be counted as one service period by master
station B. For Wi-Fi multi-media (WMM) applications, for example,
the WWM EOSP bit in the quality of service (QOS) information field
may be used as the trigger bit by slave station in the uplink
direction. For non-WMM applications, for example, the "more-data"
bit in the IEEE 802.11 frame control field may be used as the
trigger bit.
In step 46, after receiving the power save enter response from
master station B, slave station A may enter power save mode as
shown in step 48. Master station B may start buffering data traffic
for slave station A, as shown in step 50. While in the power save
mode, slave station A may not beacon and advertise its capability
as a master. Every time slave station A wakes up, it may send an
uplink trigger frame to master station B with the trigger bit
"set." Slave station A may send exactly one trigger frame in every
wake-up period. If slave station A has more than one frame in every
wake-up period, slave station A may transmit subsequent frames with
trigger bit "unset." If slave station A has no uplink data to send,
it may send a "null" uplink trigger frame with trigger bit set.
Also, all uplink frames from slave station A may have the power
management bit set to "1" in the IEEE 802.11 frame control field.
Master station B, in turn, may respond to the trigger frame with
downlink data buffered for slave station A. The last downlink frame
from master station B may the EOSP bit set. For WMM applications,
the WMM EOSP bit in the QOS information field may be used by master
station B in the downlink direction to mark EOSP. For non-WMM
applications, the "more-data" bit in the IEEE 802.11 frame control
field may be used as the EOSP indication. If no downlink data has
been buffered for slave station A, master station B may send a null
data frame with the EOSP bit set. Also, in one example, the system
may be configured so that the uplink frames sent from slave station
A with the trigger bit unset may not cause master station B to
empty a power save queue for the respective slave station.
After the maximum number of service periods permitted by master
station B is reached, master station B may stop buffering data
traffic for slave station A. Slave station A may end power save
mode in step 52. The data is buffered by master station B and
forwarded to slave station A in step 54. Slave station A and master
station B may enter the full power mode by resuming beaconing and
advertising their capability as a master station, as shown in steps
56 and 58. Both stations A and B then may compute a random back-off
and attempt to become slaves on back-off expiry. The steps shown in
FIG. 4(A) may be repeated. Since each station may rotate through
the role of a slave or master, power consumption issues on all
stations in the network may be greatly improved without
overburdening a particular station. For example, assuming that each
station spends equal time in the master and slave roles, the power
save protocol may reduce the power consumption for the slave
stations up to about 75%. Further, the protocol may reduce the
power consumption for both master and slave stations up to about
38% compared to the full power mode. The power saving may increase
as the number of slave stations increases.
FIG. 4(B) illustrates a flow chart for a power save scheme in an
asymmetrical ad-hoc network constructed according to the principles
of the invention. For example, the asymmetrical ad-hoc network may
include the cellular phone 20 as the master and the wireless
headset 22 illustrated in FIG. 3(A). As mentioned above, in the
asymmetrical ad-hoc network, only one station may have the master
capabilities. Thus, step 60 of advertising the master capabilities
and the master/slave power save enter request/response steps 62 and
64 (i.e., master/slave handshake) are implemented. For example, the
master station may return 0xFFFF in the maximum service period
field as the "master indefinite" indication. Some implementations
with pre-provisioned master/slave configurations may bypass the
master/slave handshake among the stations as their roles may have
been already decided at the production stage. Other than those
differences, the power save protocol illustrated in FIG. 4(B) may
perform steps similar to the steps performed for the symmetrical
ad-hoc power save mode shown in FIG. 4(A). For example, after
executing the master/slave handshake shown in steps 62 and 64, the
slave station 22 may enter the power save mode at step 66 while the
master station 20 may buffer the data traffic for the slave station
22 at step 68. When the slave station 22 wakes up from the power
save mode at step 70, the master station 20 may send the buffered
data traffic to the slave station 20 at step 72. If the slave
station 22 is not frequently used, power save may be greatly
increased by allowing the slave station 22 to enter the power save
mode.
In order to further improve power saving, the master station 20 may
use the sleep period of the slave station 22 to enter the power
save mode after sending a downlink frame with the EOSP bit set. For
example, upon receiving an uplink frame from the slave station 22
with the trigger bit set, the master station 20 may start a sleep
clock timer with a timeout set to expire at a certain point before
the slave station 22 wakes up. The sleep clock timer may include an
offset that may account for any timing errors in the sleep clock to
ensure the master station 20 wakes up before the next slave wakeup.
The master station 20 may exchange data with the EOSP bit set in
the last downlink frame to the slave station 22. After sending the
frame with the EOSP bit set, the master and slave stations both may
enter the power save mode. The slave station 22 may be required not
to transmit any frames after receiving the downlink with the EOSP
bit set. In this case, if both the master and slave stations have
75% power savings in the power save mode, the overall system may be
able to save power up to 75%.
Referring now to FIGS. 5, 6, 7, 8, 9, 10, 11 and 12, various
exemplary applications of the invention are shown. Referring to
FIG. 5, the invention may be embodied in a hard disk drive 500. The
invention may implement either or both signal processing and/or
control circuits, which are generally identified in FIG. 5 at 502.
In some implementations, signal processing and/or control circuit
502 and/or other circuits (not shown) in HDD 500 may process data,
perform coding and/or encryption, perform calculations, and/or
format data that is output to and/or received from a magnetic
storage medium 506.
HDD 500 may communicate with a host device (not shown) such as a
computer, mobile computing devices such as personal digital
assistants, cellular phones, media or MP3 players and the like,
and/or other devices via one or more wired or wireless
communication links 508. HDD 500 may be connected to memory 509,
such as random access memory (RAM), a low latency nonvolatile
memory such as flash memory, read only memory (ROM) and/or other
suitable electronic data storage.
Referring first to FIG. 6, the invention may be embodied in a
digital versatile disc (DVD) drive 511. The invention may implement
either or both signal processing and/or control circuits, which are
generally identified in FIG. 6 at 512, and/or mass data storage 518
of the DVD drive 511. Signal processing and/or control circuit 513
and/or other circuits (not shown) in the DVD 511 may process data,
perform coding and/or encryption, perform calculations, and/or
format data that is read from and/or data written to an optical
storage medium 516. In some implementations, signal processing
and/or control circuit 512 and/or other circuits (not shown) in DVD
511 can also perform other functions such as encoding and/or
decoding and/or any other signal processing functions associated
with a DVD drive.
DVD drive 511 may communicate with an output device (not shown)
such as a computer, television or other device via one or more
wired or wireless communication links 517. DVD 511 may communicate
with mass data storage 518 that stores data in a nonvolatile
manner. DVD 511 may be connected to memory 519, such as RAM, ROM,
low latency nonvolatile memory such as flash memory, and/or other
suitable electronic data storage.
Referring now to FIG. 7, the invention may be embodied in a high
definition television (HDTV) 520. The invention may implement
either or both signal processing and/or control circuits, which are
generally identified in FIG. 7 at 522, a WLAN interface and/or mass
data storage of the HDTV 520. HDTV 520 receives HDTV input signals
in either a wired or wireless format and generates HDTV output
signals for a display 526. In some implementations, the signal
processing circuit and/or control circuit 522 and/or other circuits
(not shown) of HDTV 520 may process data, perform coding and/or
encryption, perform calculations, format data and/or perform any
other type of HDTV processing that may be required.
HDTV 520 may communicate with a mass data storage 527 that stores
data in a nonvolatile manner such as optical and/or magnetic
storage devices. At least one DVD may have the configuration shown
in FIG. 6. HDTV 520 may be connected to a memory 528 such as RAM,
ROM, low latency nonvolatile memory such as flash memory and/or
other suitable electronic data storage. HDTV 520 also may support
connections with a WLAN via a WLAN network interface 529.
Referring now to FIG. 8, the invention may be implemented in a
control system of a vehicle 530, a WLAN interface and/or mass data
storage of the vehicle control system. In some implementations, the
invention implements a powertrain control system 532 that receives
inputs from one or more sensors 536 such as temperature sensors,
pressure sensors, rotational sensors, airflow sensors and/or any
other suitable sensors and/or that generates one or more output
control signals from an output 538 such as engine operating
parameters, transmission operating parameters, and/or other control
signals.
The invention may also be embodied in other control systems 540 of
vehicle 530. Control system 540 may likewise receive signals from
input sensors 542 and/or output control signals to one or more
output devices 544. In some implementations, control system 540 may
be part of an anti-lock braking system (ABS), a navigation system,
a telematics system, a vehicle telematics system, a lane departure
system, an adaptive cruise control system, a vehicle entertainment
system such as a stereo, DVD, compact disc and the like. Still
other implementations are contemplated.
Powertrain control system 532 may communicate with mass data
storage 546 that stores data in a nonvolatile manner. Mass data
storage 546 may include optical and/or magnetic storage devices for
example hard disk drives HDD and/or DVDs. At least one DVD may have
the configuration shown in FIG. 6. Powertrain control system 532
may be connected to memory 547 such as RAM, ROM, low latency
nonvolatile memory such as flash memory and/or other suitable
electronic data storage. Powertrain control system 532 also may
support connections with a WLAN via a WLAN network interface 548.
The control system 540 may also include mass data storage, memory
and/or a WLAN interface (all not shown).
Referring now to FIG. 9, the invention may be embodied in a
cellular phone 550 that may include a cellular antenna 551. The
invention may implement either or both signal processing and/or
control circuits, which are generally identified in FIG. 9 at 552,
a WLAN interface and/or mass data storage of the cellular phone
550. In some implementations, cellular phone 550 includes a
microphone 556, an audio output 558 such as a speaker and/or audio
output jack, a display 560 and/or an input device 562 such as a
keypad, pointing device, voice actuation and/or other input device.
Signal processing and/or control circuits 552 and/or other circuits
(not shown) in cellular phone 550 may process data, perform coding
and/or encryption, perform calculations, format data and/or perform
other cellular phone functions.
Cellular phone 550 may communicate with a mass data storage 564
that stores data in a nonvolatile manner such as optical and/or
magnetic storage devices for example hard disk drives HDD and/or
DVDs. At least one DVD may have the configuration shown in FIG. 6.
Cellular phone 550 may be connected to a memory 566 such as RAM,
ROM, low latency nonvolatile memory such as flash memory and/or
other suitable electronic data storage. Cellular phone 550 also may
support connections with a WLAN via a WLAN network interface
568.
Referring now to FIG. 10, the invention may be embodied in a set
top box 580. The invention may implement either or both signal
processing and/or control circuits, which are generally identified
in FIG. 10 at 584, a WLAN interface and/or mass data storage of the
set top box 580. Set top box 580 receives signals from a source
such as a broadband source and outputs standard and/or high
definition audio/video signals suitable for a display 588 such as a
television and/or monitor and/or other video and/or audio output
devices. Signal processing and/or control circuits 584 and/or other
circuits (not shown) of the set top box 580 may process data,
perform coding and/or encryption, perform calculations, format data
and/or perform any other set top box function.
Set top box 580 may communicate with mass data storage 590 that
stores data in a nonvolatile manner. Mass data storage 590 may
include optical and/or magnetic storage devices for example hard
disk drives HDD and/or DVDs. At least one DVD may have the
configuration shown in FIG. 6. Set top box 580 may be connected to
memory 594 such as RAM, ROM, low latency nonvolatile memory such as
flash memory and/or other suitable electronic data storage. Set top
box 580 also may support connections with a WLAN via a WLAN network
interface 596.
Referring now to FIG. 11, the invention may be embodied in a media
player 600. The invention may implement either or both signal
processing and/or control circuits, which are generally identified
in FIG. 11 at 604, a WLAN interface and/or mass data storage of the
media player 600. In some implementations, media player 600
includes a display 607 and/or a user input 608 such as a keypad,
touchpad and the like. In some implementations, media player 600
may employ a graphical user interface (GUI) that typically employs
menus, drop down menus, icons and/or a point-and-click interface
via display 607 and/or user input 608. Media player 600 further
includes an audio output 609 such as a speaker and/or audio output
jack. Signal processing and/or control circuits 604 and/or other
circuits (not shown) of media player 600 may process data, perform
coding and/or encryption, perform calculations, format data and/or
perform any other media player function.
Media player 600 may communicate with mass data storage 610 that
stores data such as compressed audio and/or video content in a
nonvolatile manner. In some implementations, the compressed audio
files include files that are compliant with MP3 format or other
suitable compressed audio and/or video formats. The mass data
storage may include optical and/or magnetic storage devices for
example hard disk drives HDD and/or DVDs. At least one DVD may have
the configuration shown in FIG. 6. Media player 600 may be
connected to memory 614 such as RAM, ROM, low latency nonvolatile
memory such as flash memory and/or other suitable electronic data
storage. Media player 600 also may support connections with a WLAN
via a WLAN network interface 616.
Referring to FIG. 12, the invention may be embodied in a Voice over
Internet Protocol (VoIP) phone 650 that may include an antenna 618.
The invention may implement either or both signal processing and/or
control circuits, which are generally identified in FIG. 12 at 604,
a wireless interface and/or mass data storage of the VoIP phone
650. In some implementations, the VoIP phone 650 includes, in part,
a microphone 610, an audio output 612 such as a speaker and/or
audio output jack, a display monitor 614, an input device 616 such
as a keypad, pointing device, voice actuation and/or other input
devices, and a Wireless Fidelity (Wi-Fi) communication module 608.
Signal processing and/or control circuits 604 and/or other circuits
(not shown) in VoIP phone 650 may process data, perform coding
and/or encryption, perform calculations, format data and/or perform
other VoIP phone functions.
VoIP phone 650 may communicate with mass data storage 602 that
stores data in a nonvolatile manner such as optical and/or magnetic
storage devices, for example hard disk drives HDD and/or DVDs. At
least one DVD may have the configuration shown in FIG. 6. The VoIP
phone 650 may be connected to memory 606, which may be a RAM, ROM,
low latency nonvolatile memory such as flash memory and/or other
suitable electronic data storage. The VoIP phone 650 may be
configured to establish communications link with a VoIP network
(not shown) via Wi-Fi communication module 608. Still other
implementations in addition to those described above are
contemplated.
In accordance with various embodiments of the invention, the
methods described herein are intended for operation with dedicated
hardware implementations including, but not limited to,
semiconductors, application specific integrated circuits,
programmable logic arrays, and other hardware devices constructed
to implement the methods and modules described herein. Moreover,
various embodiments of the invention described herein are intended
for operation with as software programs running on a computer
processor. Furthermore, alternative software implementations
including, but not limited to, distributed processing or
component/object distributed processing, parallel processing,
virtual machine processing, any future enhancements, or any future
protocol can also be used to implement the methods described
herein.
It should also be noted that the software implementations of the
invention as described herein are optionally stored on a tangible
storage medium, such as: a magnetic medium such as a disk or tape;
a magneto-optical or optical medium such as a disk; or a solid
state medium such as a memory card or other package that houses one
or more read-only (non-volatile) memories, random access memories,
or other re-writable (volatile) memories. A digital file attachment
to email or other self-contained information archive or set of
archives is considered a distribution medium equivalent to a
tangible storage medium. Accordingly, the invention is considered
to include a tangible storage medium or distribution medium, as
listed herein and including art-recognized equivalents and
successor media, in which the software implementations herein are
stored.
While the invention has been described in terms of exemplary
embodiments, those skilled in the art will recognize that the
invention can be practiced with modifications in the spirit and
scope of the appended claims. By way of example, the stations of
the inventions may be any device capable of wireless communication
and standards other than the IEEE 802.11 standard may be used to
implement the invention, such as Bluetooth and similar standards.
These examples given above are merely illustrative and are not
meant to be an exhaustive list of all possible designs,
embodiments, applications or modifications of the invention.
* * * * *